[core] Fix checkstyle for Core miscellaneous (#901)

core/src/main/java/com/yahoo/ycsb/BasicDB.java

core/src/main/java/com/yahoo/ycsb/ByteArrayByteIterator.java

core/src/main/java/com/yahoo/ycsb/ByteIterator.java

core/src/main/java/com/yahoo/ycsb/DB.java

core/src/main/java/com/yahoo/ycsb/DBException.java

core/src/main/java/com/yahoo/ycsb/DBFactory.java

core/src/main/java/com/yahoo/ycsb/DBWrapper.java

core/src/main/java/com/yahoo/ycsb/GoodBadUglyDB.java

...src/main/java/com/yahoo/ycsb/InputStreamByteIterator.java

core/src/main/java/com/yahoo/ycsb/RandomByteIterator.java

core/src/main/java/com/yahoo/ycsb/Status.java

core/src/main/java/com/yahoo/ycsb/StringByteIterator.java

core/src/main/java/com/yahoo/ycsb/TerminatorThread.java

core/src/main/java/com/yahoo/ycsb/UnknownDBException.java

core/src/main/java/com/yahoo/ycsb/Workload.java

core/src/main/java/com/yahoo/ycsb/WorkloadException.java

core/src/main/java/com/yahoo/ycsb/package-info.java